1. Field
The present invention relates to controlling a display device.
2. Background
In graphics systems, a display controller sends image frames and timing signals to a display device. The display device displays the image frames at a refresh rate determined by the timing signals. The display controller can be included in or coupled to a graphics processing device such as a graphics processing unit (GPU). In some situations, the display can become static. That is, a number of successive image frames to be displayed are identical. This situation may arise, for example, if an extended period of time has passed before a user has interacted with the system, e.g., when a user does not interact with a laptop computer for a specified period of time.
When the display becomes static, the elements of the graphics system can be switched to a self-refresh state. In the self-refresh state, much or all of the display controller and/or GPU can be powered down. On the display side, in the self-refresh state, the display device can capture the last received image frame in a buffer. Moreover, the display can also locally generate timing signals used to refresh the display. Thus, in the self-refresh state, the display essentially operates independently of the display controller.
When the display ceases to be static, i.e., when the image frame to be displayed changes, the graphics system transitions back to a normal power state. During the time in which the elements of the system were in the self-refresh state, the clock signals of the display controller and the display may have become out of sync. Thus, there may be a delay in updating the display when the system switches back to the normal power state.